The present invention generally relates to an improved seat ring assembly for ball valves or gate valves.
Conventional seat ring assemblies for ball valves or gate valves are characterized by a synthetic resin seat ring insert which is fixedly inserted into an annular groove cut in the interior conical surface of the seat ring. The synthetic resin seat ring insert projects beyond the interior conical surface of the seat ring and sealingly engages the external surface of the valve body. The contact between the synthetic resin seat insert and the valve body, however, is often not sufficient to provide a good seal. Moreover, when the synthetic resin seat ring insert is worn due to friction or damaged and even broken by a foreign object, the seal is greatly reduced or eliminated.